Shiro Hori

Identification of amino acids in humic acid

Abstract Davidson, Sowden and Atkinsonl) in 1951 reported on the amino acids in the three soil organic matter fractions, and Stevenson, Marks, Varner and Martin~) in 1952 reported on the identification of eight amino acids from clay-adsorbed organic colloids in Brookstom slity clay loam. Also, some investigations on these amino acids have been carried out in our laboratory.

Purification of humic acid by the use of ion exchange resin

Abstract The humic acid fraction, extracted from soil by alkali or neutral salt solution and acid-recipitated, is generally contaminated with a considerable amount of inorganic matter. The presence of the inorganic matter is often undesirable for studies on humic acid. The inorganic matter is generally taken off by ultrafiltration or electrodialysis. But these methods take time and are unsuitable for the bulk preparation of humic acid.

Changes in proline-14C metabolism in barley seedlings germinating at low temperature

Abstract Changes in the metabolic pattern of proline-14C were examined in barley seedlings germinated at the low temperature of 2°C (LT) and compared with those germinated at 25°C (HT). In the LT shoots. proline-14C incorporation was higher in the cationic fraction and lower in the acid-neutral fraction than that of HT, respectively. More proline-14C of LT was converted to other amino acids, especially to acidic amino acids in free amino acid state, than was the HT proline-14C which had a comparatively wide distribution. In the LT protein fractions. more proline-14C was incorporated into the cytoplasmic protein than into the cell wall protein. On the contrary, the radioactivity of the lIT cell wall increased more distinctively. proline-14C in the two proteins of LT was a little less converted to other amino acids than in those of HT. A little higher radioactivity was found in the aspartate and glutamate of the LT protein hydrolysates. The hydroxyproline which is closely related with proline had a little l...

Some characteristics of rapidly labeled nucleic acids in barley coleoptiles grown at cold temperature

Abstract Some plants, for example winter wheat, require a low temperature period during the early germination and establishment stage to further flowering. In another case, the incubation of plant seeds at low temperature promotes their flowering. The phenomenon was named “jarovization” first by LYSENKO and WUYTE later suggested the name “vernalization” (1).

Some characteristics of rapidly labeled nucleic acids in Barley plants at vegetative and reproductive growth stages

Abstract It is convenient to obtain barley plants at various growth stages by utilizing low temperature (vernalization) and photoperiodic treatments. Protein synthetic activity and photosynthetic products of barley plants at vegetative and reproductive growth stages, by the use of these treatments, are being studied (1).

Studies on the effect of humic acid on availability of phosphorus

Abstract It is believed that some organic compounds form complexes with iron and aluminum and prevent the fixation of phosphate applied to soils.

SOME ASPECTS ON THE NATURE OF HUMIC ACID

Abstract For the extraction of humic acid from soils, solutions of sodium hydroxide or neutral sodium salts of inorganic and organic acids such as sodium fluoride, sodium oxalate and sodium pyrophosphate have been used most generally.

The Gamma-Ray Dose-rate Effect in the Sprout Inhibitionof Potato Tubers

The gamma-ray dose and dose-rate effects and the loss of weight in the sprout inhibition of potato tubers were studied. The potato tubers used for this experiments were “Danshaku” variety which were yielded in October in Hokkaido.The irradiation was carried out in the dose-rate range from 5 × 102 R/h to 5 × 105 R/h changing the dose from 3 kR to 15 KR in December of 1975 and 1976. 60Co-source used for those irradiation were 7300 Ci and 13000 Ci of a rod type one (1.4 cm ∅ × 30 cm), respectively. The irradiated potato tubers were stored for 5 to 7 months in dark natural condition, and their sprouting and their weight variation were observed.The obtained results are summarized as follows:1) The time of sprouting of the irradiated potato tubers is delayed compared to that of non-irradiated ones (control). The more the dose and the higher the dose-rate, the delayed time becomes larger. The potatoe tubers irradiated to 6 kR under 5 × 104 R/h are late about 60 days in sprouting from non-irradiated ones (Fig. 1).2) The sprout inhibition is more effective not only by heavier irradiation dose, but also by irradiation under higher exposurerate (Fig. 2 and Fig. 3).3) The necessary and sufficient dose for the sprout inhibition is estimated to be about 10.5 kR for exposure-rate of 5 × 103 R/h, and it increases rapidly for the lower exposure-rate, while it decreases with the rate of about 2 kR per one order of magnitude of exposure-rate for the higher exposure-rate (Fig. 4).4) The rate of weight loss of irradiated potato tubers is small compared to that of non-irradiated ones, and ones more irradiatedshow less rate of weight loss (Fig. 5 and Fig. 6). The exposure-rate dependence in weight loss is not apparent (Fig. 7).

The Gamma-Ray Dose-Rate Effect in the Sprout Inhibition of Onion Bulbs

防止の線量率効果に関する研究も少ない。筆者等は60Co.線源 (1.4φ×30cm、棒状約8000Ci) を用いて昭和50年と昭和51年に102～105R/hの範囲で種々の線量に対する発芽防止の線量率効果を観察した。試料の玉ねぎは “泉州甲高” (6月中旬採取) 、照射は7月下旬～8月上旬に実施し、照射後、自然状態で保存、10～20日毎に発芽を観測した。線量率を変えるには線源と試料との距離を調整して変えた。高線量率照射の場合は試料が線源に近接するので、玉ねぎ2～3個を紙筒に入れ、底盤部と頂部が円筒軸に一致するように重ね、線量のパラッキを少なくするようにした。低線量率照射の場合はプラスチック製籠に一重に並べて照射した。発芽は照射線量が低い程早く、日が経つにつれて発芽率は高くなる (Fig.3) 。また、照射線量率が高いほど発芽しにくい (Fig.5) 。発芽防止の限界線量は、照射線量率が1×103R/hのとき約2000Rで、これより低い線量率では急速に高くなり、高い線量率ではゆるやかに低下する (Fig.7) 発芽率の観察を終了後 (照射後8ケ月後) 、発芽しなかった玉ねぎを切断して内芽の褐変を観察し、その長さを測定し、褐変の長さの分布曲線を求めた (Fig.8) 。その結果、褐変の長さは照射線量率に依存しており、低線量率で低線量照射したものの褐変は太く長く、高線量率で高線量照射したものは短いことが判明した (Fig.10) 。

Changes in some enzyme activities and the nicotinamide nucleotide coenzymes in barley seedlings during vernalization

Abstract Respiratory metabolism was investigated by determining the following enzyme activities and nicotinamide nucleotide coenzyme contents in barley shoots (Hordeum vulgare L., var. Akashinriki) during vernalization : glucose-6-phosphate dehydrogenase, phosphoglucoisomerase, enolase, isocitrate dehydrogenase, malate dehydrogenase, and glutamic dehydrogenase. The activities of glucose-6-phosphate de hydrogenase and phosphoglucoisomerase in vernalized shoots were slightly lower than those in non-vernalized samples. Malate dehydrogenase activity increased gradually in vernalized shoots and was always higher than in non-vernalized shoots. Activation was found in enolase, isocitrate dehydrogenase and glutamic dehydrogenase after a long vernalization treatment. The contents of total nicotinamide nucleotide coenzymes increased during the early germination stage in both treatments, then decreased gradually in the succeeding stage.